how do i seek by a single frame instead of going to the beginning and end of sequence?

Your question is not clear. As Jeff the Left and Right arrow move you frame by frame.

If you are talking about entering a time code number, click on the timecode display and you can enter a number.

When i'm trying to export a video and I try to seek a frame, the marker just jumps to the beginning or end of the sequence? Any idea how to seek by frames?