Here is a bit from southern fried Cathoilcism blog
What is Lent?
Lent is a time when all throughout the Church prepare to celebrate Easter through penance, prayer, fasting and alms-giving. Traditionally, the season of Lent lasts forty days (not counting the Sundays of Lent), from Ash Wednesday until the Easter Vigil (the night before Easter Sunday). The word Lent is from an Anglo-Saxon word lencten, which means "spring." Observance of Lent can be traced to the earliest days of the Church, when Christians willingly joined catechumens (those seeking baptism) in a period of intense preparatory prayer and fasting in the weeks before their baptisms, which were performed during the Easter Vigil, in the pre-dawn hours of Easter Sunday.
What is the point of Lent? Is it biblical?
The point of Lent is that it is a time of prayerful reflection and conversion (turning away from sin and back to God). In imitation of our Lord Jesus Christ, who spent forty days fasting and praying in the wilderness before beginning His public ministry (see the gospels of Matthew, Mark and Luke), we spend the forty days before our annual celebration of the Lord's Resurrection (i.e. Easter) in fasting, prayer and sacrifice. The number 40 is important in the Bible because it symbolizes preparation and renewal. For example, Noah spent forty days and forty nights in the ark (Genesis 7:4, 12, 17; 8:6) and Moses spent forty days and forty nights on Mount Sinai when receiving the Law from God (Exodus 24:18; Deuteronomy 10:10).
Do I have to "give something up" during Lent?
It seems that everybody - even those who know the least about Catholic Christianity - knows that Catholics traditionally give something up during Lent. In fact, it becomes a ridiculously common question for Catholics to ask one another "what did you give up?" during this season. Truth is, you are not required to give up something for Lent. What you are required to do, is to do penitential acts - making temporary sacrifices in an effort to draw closer to God. For many people, they may willingly give up something that they enjoy as a penance during Lent. This is certainly a good practice. For others, however, they may choose to do penance by setting their alarm extra early to get up and pray every morning, or by setting aside extra money each week for the poor or the Church. If you haven't decided what to do on this front, might I suggest that you pray and ask God what penance(s) He would have you do during Lent?
What about meatless Fridays?
You have a lot of leeway on your personal disciplines during Lent, but Fridays, however, are a different story. Whether you realize it or not, every Friday of the year is supposed to be a day of penance for Catholics, so Lent isn't all that different. Yep - that's not just a "pre-Vatican II" thing - current church discipline actually requires that on every Friday of the year, according to canon law and in recognition of Christ's sacrifice on the cross, you should either refrain from eating meat or do some other penance (such as praying the Stations of the Cross, saying extra prayers, or some other offering). On the Fridays of Lent, however, you don't have a choice: you are obliged to refrain from eating meat. The cool thing about this is that this is a communal discipline: in other words, while abstaining from meat on Fridays may or may not be difficult sacrifice for you, personally, the cool part is that we're joining the worldwide Church in a very ancient Catholic discipline.
Why do we eat fish on Fridays?
You certainly don't have to eat fish on Fridays. You could simply go vegetarian each Friday. But the point is refraining from eating meat. Eating fish is allowed on Fridays because, due to longstanding tradition, fish is not considered meat. The fish is an ancient Christian symbol and eating fish (and other seafood) on Fridays has long been allowed. Of course, if eating seafood is actually a treat for you (and you know who you are!), you might strongly consider skipping proteins altogether on Lenten Fridays. After all, the point of a discipline like this is penance not decadence.
What are "days of fast and abstinence"?
During the Lenten season, we are encouraged to fast, pray and give alms (money to the poor), seeking to amend our Christian lives - the three traditional disciplines of Lent. But on two days in particular, the Church requires that we all fast and avoid meat. They are: Ash Wednesday and Good Friday. On these days, Catholics should fast (eating only one small meal, if needed). If they do eat a small meal, it should be meatless.
Are the Sundays in Lent part of Lent?
Many people ask if they can "cheat" on the Sundays of Lent? In other words, they want to know if they have to practice penance on the Sundays of Lent. Well, technically, Sundays are always a celebration of Jesus' Resurrection - sort of "mini-Easters," if you will - so Sunday is never officially a day of penance. In fact, on the Church's calendar, the Sundays during Lent are called the Sundays in Lent instead of the Sundays of Lent. So, it is really up to you. Lent is a season geared towards doing penance and turning towards the Lord. If you feel that you are "cheating" on your penance, then you shouldn't do it. Follow your conscience.