how do i select one of the points to create another bit of path of it ?

don´t really know what u mean. u mean u take one point of ur path and from that point u start another line?

naw so im making my line and realise
o i want to go back to my first point because my line is too short
for example

delte path? oO
Or just STRG + ALT + Z ?

naw because i like my current path but i want to add some onto the bottom

arrr now I know what u mean. I`M afraid I can´t help here.

There is a specific tool for it:

or hold alt and press the point if thats what u mean