Hey pavithra.; Sometines babies skip the crawling step altogether and immediately learn to stand . So don't stress . Although u can try showing ur child how to crawl by doing it urself . By watching u ur will learn . Even if he doesn't its ok .

Daily; lay him down on his tummy for some time and you can encourage him to move by toys or his fav stuff. If you feel he is getting irritated then stop doing it fid the day.

Don’t put too much pressure on him but you can buy some moving musical toys and put them in front of him while he lays down on his tummy.