Combining multiple sketch of arduino

i have 3/4 sketch but i want to combine it into 1 single sketch. how do i do it ? is it just copy and paste ?

Have a look for the numerous tutorials on this subject. Grumpy Mike's is one that springs to mind.

0.75 of a sketch is never going to work ;)

This Simple Merge Demo may be of interest. Don't try to merge more than 2 programs at once.