I have a nikon d3400 and i'm trying to take a picture using the self timer?

Every time that i try to take a photo in the timer control it still only lets me take a normal photo. Please help by explaining what i need to do and what the problem is in detail.

Read the manual, it has all you need to use the timer, my D3200 manual does.

What were you expecting? The self timer only delays the taking of the picture. Everything else is the same.

Perhaps if you described what you want to happen then maybe we can make suggestions on how you can setup the camera to get it right.

Check out page 6 of the owners manual.

Read The Owner's Manual.