If-Then clause using cells in Excel

My situation:

I have some colums in excel containing different values, for each row i want to check colum1,2,3,etc and then i need an if-then clause that works like this:

if (value in colum1=="something")
then 
fill cell x with "something else"

I'm not asking how to do it in details, but if you could tell me what excel functions i should look into to make it possible it'd be great. (I have never worked with excel before and i didnt find much googling)