Answer:
first of all, you need the sims 1 installed.
1. Insert the disk.
2. There should be an autorun. This will lead you to an installation wizard.
3. Agree to all unagreed checkboxes, insert the code [on the back of the leaflet given with the box]
4. Easy enough, you should be done. Well done, go play.
Note~ if it does not automatically run, you will need to open My computer > Disk [usually E: drive on my own computer.] This should then go to the wizard.