First time building a smallll wall to replace rotted out RR ties...Ties are used as edging (1 tie high) so wall block (the block with the lip in the back tat is so popular today) needs to go no higher...maybe 2 high... So I am planning on removing the ties, put some sand down then the first layer of block 'base' and then staggering the joint lines, add the 2nd layer...then backfill with topsoil/mulch... Does this sound like the right way to do this or do I need crushed stone or to do something else??? Also where would the ideal place be to purchase the retaining wall blocks??? HD or Lowes??? Or would the supply guy for the mulch/topsoil have something like that???