What soil should I be using in my bed? Local topsoil is alot of clay and sand.
Native soils, most generally consist mostly of clay, silt and sand. Good place to start. Like Eric says add some compost and you should be good to go. Yes, those types of soils are what most of the worlds vegetables are grown on.
Clay is a very fine material. Small particle size. Silt has particles larger, and sand has particles even larger. Take a quart glass jar and fill it about 3/4 full of that local soil, then fill the jar with water and shake it up very well. Now set it down and don't touch until all the sediment settles. You should be able to see the layers of clay, silt and sand and get an idea how much of each the soil contains.
[url=https://websoilsurvey.nrcs.usda.gov/app/]Clark County Soils[/url]
Check this site and see what you can learn about the local soil.
Actually in a hot dry climate like Las Vegas a soil with 20-30% clay will be a plus as it holds moisture well. Clay is also high in minerals. Clay is not really the "Dirty Word" that seems to be the popular notion on the internet. Only when soils are above 50% clay is it a big problem.
I don't know what you are placing your beds on, but I always suggest placing them on the local soil and using no barrier. This way the roots can go deep. Many of our garden plants send some roots to the 3 foot level and beyond. If the roots can go down, you won't need to water as often.
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-