Don't worry about getting the wires into the bend at first.  The first thing you need to do is get a proper length with a little extra for mistakes, and then pre-cut all your wires, ground included.  If you forget to mark the neutral, you can do that later with a ohmmeter.
You need to get a pull rope into the conduit first, a fish tape works well for this.  Some people use a string with a rag on it, and a vacuum cleaner to suck the rag through the conduit, I have never tried this.
Then carefully tape the wires to the pull string or rope.  You could use the fish tape too.  I usually make the ground extra long, make that one wire into a hook, and tie it to the string and tape it, and then tape all the other wires to the ground wire.  Tape them so they are tapered so it's smooth and won't catch in the conduit.
Then with a helper, someone pushing, someone pulling the string, pull the wires through.  Don't worry about that bend (it's called a "LB") just pull the string and the wire on the outside of the building.  Once you get the end there, keep pulling, estimate how much wire you need in the building, and pull that all out on the outside of the building.  Then if the panel is just on the other side of the wall, take all the tape and the string off, and you can then push each wire individually into the panel through the LB.