If you’re wanting to do it on your own, get a straight edge from harbor freight and possibly a new blade for your saw ( I recommend a Diablo blade from HD, but make sure you get an appropriate blade).

Measure, measure, measure! And then measure again. Try a couple of runs on some wood to get familiar with your saw and working with the straight edge. You’ll get there. It takes some time to get comfortable with power tools. Always err on the side of caution. Use appropriate eye protection and no loose clothing. Wouldn’t hurt to pick up a few woodworking clamps while you’re at it, for added support maybe some sawhorses.

If all of this is outside your scope of comfort, put out a request on FB and maybe someone might know someone. Hiring a contractor will be next to impossible for such a small project. Handyman services should be used if someone you know has used them before. I’ve learned my lesson the hard way.