This one's pretty straightforward, but it never hurts to reinforce it.
There are several ways in Turkish to state a need or an obligation to do something. It can be done with simple words tacked on to the end of a sentence following a verb (usually in infinitive form), such as "lazım", "gerek" or "mecbur". This is probably the easiest for a beginning student to use. An example would be: "Bugün çalışmak lazım", or "Today one must work/Today working is necessary". "Lazım" could easily be replaced with "gerek" and it would invoke the same meaning. "Mecbur" is a bit stronger, in that it conveys an absolute necessity, or obligation. "Lazım", in particular, seems to be very much in use in Pop music. Tarkan uses it a lot in his songs. I don't think I'm exaggerating when I say that half of his songs that I've heard use the word.
But the same thing can be said using and actual verb conjugation. I could also say "Çalişmam gerekiyor" to mean "I need to work". Here we're actually conjugating "gerekmek" ("to be necessary/to be needed") and changing the infinitive of "çalışmak" to "çalışmam", or "my working", so it literally is "Working my is necessary".
Finally, there is another, perhaps more sophisticated way to specify need, and that's with the Necessitative Mood, which can be used in both simple present and past tenses. This also is very easy to do: we use "meli/mali" as part of the verb conjugation. So, for a "meli/-mek" example verb, "Girmeliyim" is simply "I must enter". An example of a "mali/-mak" verb would be "Bakmalıyım" ("I must look at").
Changing these to the past tense is also simple: "Girmeliydim" ("I must have gone into/entered") and "Bakmalıydım" ("I must have looked at").