A wheel chock is a slot for the front tire. It keeps the tire straight while the motorcycle is in transit. Start by attaching a chock to your trailer or truck bed. Position it at the back of the bed and center it. Then bolt it down.  Wheel chocks are available at automotive stores or online. Some trailers have holes for attachments like wheel chocks already in place. Look for pre-made holes for the bolts. You can also install a wheel chock temporarily if you don’t want to worry about attaching screws and bolts. Position it the same way, then tie it down with ratchet straps. The strap tension will keep the chock secure. Use a specialized motorcycle ramp that can support the weight of your bike. Attach the ramp to the trailer bed. Then gently roll the motorcycle up into the truck bed. Don’t let go of it at any point or it will tip over.  This is much easier with two people, one holding on each side. Some utility trailers have built-in ramps, or are low enough that you won’t need a ramp. Don’t use wooden planks for this job. They may not support the weight of the motorcycle. If you’re loading the bike into a pickup truck, remove the tailgate if you can. They sometimes can’t handle the weight of a motorcycle, and could break. Roll the bike to the back of the trailer and rest the front wheel in the chock. On most chocks, the mechanism clicks when the front wheel fully enters it. When you hear this click, the bike is in the correct position. Do not lower the kickstand. You can put it out temporarily while you gather your equipment, but raise it before you tie the bike down.

Summary:
Attach a wheel chock to the back of the trailer bed. Load the motorcycle into the trailer with a ramp. Position the front wheel into the wheel chock.