Loads of stuff on the net about it now a days, I learnt about 13 years ago from pictures in magazines and watching JMC in 'dirt' the video 😆
-Practice the lift of the front wheel first, keep doing this until your really confident with lifting the front wheel.
-Now practice the lift of the rear wheel. Coast along at a 'reasonable' pace and practice lifting/unweighting the rear wheel off the ground by pressing 'down back and up' on the pedals.
-Then connect the 2 together. Lift the front, then try and 'push the bars away from you' at the same time as unweighting the rear. Try and land rear wheel first or you may go over the bars. also have something to physically hop over eg. an old shoe box or something to start.
That probably makes no sense what so ever 😉