If you have no previous experience with OpenComputers, you should take a look at this guide.
You need to craft at minimum the following parts for your robot:
- Computer Case (Tier 2)
- EEPROM (Lua BIOS)
- CPU (Tier 2)
- Memory (Tier 1) x2
- Hard Disk Drive (Tier 1) with OpenOS installed
- Internet Card
- Geolyzer
- Inventory Upgrade
- Inventory Controller Upgrade
- Crafting Upgrade
Unless you really know what you're doing, you probably need these too:
Place all these parts in an Electronics Assembler. Power and start the assembler, and when your robot is finished, place it in the world and power it on.
Now that your robot is running and OpenOS is installed, just paste this into it. (If your Roboserver is running but you don't have internet access, you can use the local install instead.)
After answering a few questions about your robot, it will connect to the server you started in the previous step. Congratulations, you're done! Next check out these tips on how to use the Roboserver.