Transport bar start point and looping parts of pattern

I can’t seem to find this anywhere in the manuals. can anyone tell me how you get the transport bar to start from another point in the pattern other than zero. Also how does one get the transport to loop on a particular highlighted part of a pattern?
Any help much appreciated.

shift + space bar will start a pattern from the line you are on. the block loop function is in the upper left corner, underneath the transport buttons.

thank you very much.