If all you need is to raise the handlebars, buy a threadless stem riser. $12 to $30 on Amazon or Ebay, your bike shop will likely have one as well.
If you're going to buy a suspension fork, you can get an extended steerer tube fork that will take care of raising the handle bars. This is more complicated. It requires measuring, an adapter to attach your brake caliper and spacers for the stem attachment. You'll need a cutting jig to cut down the steerer tube and other tools for star nut install. You'll need to study up on all that to install or take it to a bike shop.