In most cases you wouldn't put the pole through the curtains but hang the curtains from rings on the pole. But there are lots of differents ways of attaching them, little crocodile clips, ties, buttons...etc.
Cut your fabric to double the width of the window plus 4cm seam allowance. If your material is not wide enough you will have to make a join, allow another 4cm for this and cut two drops. If there is a pattern on the fabric you might have to match it up on your seam, don't forget to allow extra fabric for this. Obviously if you want two curtains on the window you make them half the width. Always allow for a little overlap each side since your curtains will normally cover the window and more.
Measure from your pole to the point where you want the bottom of your curtain to be. Add 10cm for a header and 20cm for a hem, and you have the length of your drop.
If the fabric has selvedges on it, either cut them off, or if they are part of your seam allowance, clip them at 10cm intervals to avoid puckering at the seams.
First join any drops you might need to make the curtains wide enough (prob not necc with a small window) then iron the seams flat. Turn over the sides of the curtains 1cm and press into place, then repeat, so you have pressed a double 1cm hem. Sew this down.
Next turn over the top of the curtain 10cm and press, and the bottom of the curtain 10cm, press and repeat (only repeat at bottom). Sew down.
Pin heading tape of your choice to the inside of the top hem, tuck the ends under and sew on carefully so as not to sew over the tapes. Afterwards pull out the tapes a little at one end and tie them together, then do the same at the other end and you pull them out to get your curtain gathered to the desired width. You can then put hooks through the tape and attach them to the rings on your pole.
More complicated ways of attaching the curtain to your pole may require a different treatment for the top hem.
I myself would use flat fell seams for any joins in the curtains, but this may be more than your experience stretches to at the moment!