If you are having trouble updating, you might try uninstalling MCModKit and redownloading and installing from scratch.

1. Open the Control Panel
2. Click Add Remove Programs or Uninstall a program
3. Select MCModKit from the list and click the "Uninstall" button
4. Select "Remove the application from this computer" and click "OK"
5. Download the latest version from https://www.mcmodkit.com/Download.aspx
6. Open the zip file that was downlaoded and double click on the MCModKit file inside it

Some mods don't play nice together. This is typically the issue when you have selected more than one mod and Minecraft won't start. We recommend selecting adding just mod at a time. After verifying Minecraft successfully launches you can try adding another mod. Continue to do this until Minecraft won't work and you will have identified the mod that doesn't play nice.

This is a problem with ClickOnce deployments on your computer. You can fix this problem by deleting the files in the following folders:

C:Users\username\AppData\Local\Apps\2.0\
C:\Documents and Settings\<user>\Local Settings\Apps\2.0
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files

Then run this tool from Microsoft to fix Windows corruption errors.

http://support.microsoft.com/en-us/kb/947821/en-us

Finally, uninstall and reinstall MCModKit.

Click on the "Maps" tab under the "Install Mods" tab.
Click "Install" next to the map you want to install.
Enter the name of the folder you want to install the map in (or just press enter).
Launch Minecraft and click "Singleplayer".
Maps are just saved games (or worlds) and they are ordered backwards from the last time they were played so you may have to scroll pretty far down the list to find the map you installed depending on when it was created.
Select the map and click "Play Selected World"!

You don't need to install Forge yourself. We have done all the work for you!  So, just click an Mod and play it!  You can still find Forge under the APIs.  You need to click the Mods tab and then click "Show APIs". You should see it then!

They simply aren't available yet.  We are watching for them also.  We have about 13 1.8 mods, but alot of really amazing mods have not been updated.

The developers have  not created them yet.  We are watching for them, as soon as they are available, we will put them up!  If you see them before we do, please send us the link!  It will greatly improve the speed at which they are updated.