You need 4mm knitting needles, and stylecraft special dk wool
Look up some YouTube videos for long tailed or thumb cast on method, that will get you started.
Then you want some simple videos on how to do garter stitch/knit stitch.
Start with just casting on 20 stitches and knitting a load of rows till you don't have to think about your hand position or which way to move the wool around the needle.
Once you've got the hang of knit, look up Purl stitch and do the same again.
All knitting is a combination of knit and purl stitch, knit you are making the knot at the back of your piece, purl you are making a knot at the front.
If you just do knit for every row you get a thick, stretchy, bouncy length of knitting.
If you do a row of knit then a row of purl, you get a very stable, neat and less stretchy piece in a pattern called 'stockinette' stitch.
If you alternate stitches so you do Knit, purl, knit, purl you get a ribbed piece of work like the brim of a beanie hat or a cuff of a sweater.