HELP!! New home/pool owner!!

Hi...We just purchased a new home and it has an above ground pool. The pool was used a few months last summer and then the pump/filter broke. Old owner fix it, but by the time it was fix he said pool got some sort of yellow/brown algae in it. So he left it...I drained it today in order to clean out the leaves, tadpoles and other gunk. It isn't completely drained yet, but noticed there is a gritty sand feeling substance on the walls & floor. It is a vinyl lined pool. I tried scrubbing a little, but it would come off and was afraid that I would tear the lining. Can someone please give me easy layman terms on how to either get rid of this stuff or what I need to so. Do I need to fill the pool and swim like normal and just add the "normal" chemicals or is there something I can do or get to dissolve the stuff off of the pool. Any help you can give me would be so very welcomed!