In MS-DOS mode, go to the directory you installed Command & Conquer in and type "c&c funpark". When the game begins, select START NEW GAME and choose either side for five new missions.
In order to use this cheat you will need a Communications Center. First build something you want but don't deploy it. Click on a building that has at least one block of building room. Partially cover that building with the menu bar.
Now click on the building which you want to deploy. Move this building toward the building which is partially covered by the menubar. Now bring your mouse onto the menubar and on the map. You can deploy anywhere you see a symbol similar to a "no smoking" sign, unless told otherwise by the computer.
NOTE: This code only works in versions 1.18p or earlier.
Let a silo fill up half way then sell it. You'll get lots of cash for the silo.
To sell a vehicle, place it in a repair bay, then choose the $ cursor and place it over your vehicle. You'll get about the half the value back.
To find a space ship, go to the GDI level 6: Czech Republic. Build a normal base. Blow up all SAM sites. When you get the airstrike option, use it to attack the bottom-left corner. If you don' see a silver ship, attack with airstrike a little higher than you did before. You should see a silver space ship that crashed.
You can steal the enemy's harvester by capturing the refinery while the harvester is depositing money into it. This comes in handy on earlier missions when you cannot build more harvesters.