I've downloaded a Red Alert & Command and Conquer. I cannot play the game.

@bh2311 

Are you sure that's "Red Alert", as in, the first Red Alert game? Because as far as I know, the "black screen" thing is a Red Alert 2 issue.

This collection has a lot of games, developed over a span of fifteen years, on a large number of different game engines, for a large number of different systems, so you have to make sure to specify exactly which game you're talking about, otherwise it's really hard for us to give accurate tech support.

That said... might as well give you all of the fixes, so you can get them all running.

Command & Conquer 1, Red Alert 1 and Tiberian Sun have all been upgraded with community-created unofficial patches that fix a lot of their bugs and compatibility problems. For Red Alert 2 there's a more general patch that solves a lot of its graphics problems. You can find them here:

Command & Conquer 1:

• Nyerguds' C&C95 v1.06c revision 3 patch (which also adds bonus missions originally exclusive to the Playstation and Nintendo 64 versions of the game)
  Note that this patch fixes two quite common and completely fatal game crashes (top-of-map reconnaissance crash, stealth crash), so installing it is strongly advised.
• An upgrade for the patch's config tool and cnc-ddraw component have been provided by FunkyFr3sh. Apply it after installing the patch.

Red Alert 1:

• Funkyfr3sh's automatic Red Alert 1 patcher/installer (The thread also has briefing videos for the expansion missions, converted from the Playstation version of the game)
• Nyerguds' main.mix cleanup for TFD/TUC (Not really needed, but cleans up about a gigabyte of unnecessary files in the RA1 folder. Unpack in the game folder, run "patch_main.bat", let it finish, and then delete the files you extracted.)

Tiberian Sun:

• Funkyfr3sh's Tiberian Sun patch

Red Alert 2:

• The graphics system patch DDWrapper is known to solve a multitude of graphics problems, including the "black screen" issue.
  Download the zip file and extract "ddraw.dll" and "aqrit.cfg" into your game folder. Then, open the configuration file "aqrit.cfg" in Notepad, change the "ForceDirectDrawEmulation" option to 1, save the file, and try running the game again.
• If you still have problems with RA2 even after this, I advise installing the CnCNet online play installer for RA2/YR. Even if you're not interested in online play, it comes with a bunch of automatic fixes, and has a configuration tool which offers more choices in graphics fixes than just DDWrapper, so if one doesn't work you can just try if some of the other options do the trick.