Can you read and understand English? If your English is insufficient you should start to learn English when you still want to work with Computer and to develop software. The error message is as clear as the sun's shining at noon. So, what does the message say?
1) Cannot open Eclipse Marketplace. Why? Have you check this link?
2) Cannot complete request tohttp://marketplace.eclipse.org/catalogs/api/p. Why? Have you check the given link?
If you try to dial a ghost number and you get "beep...beep...beep" then you cry for help.... Is that not to much to ask you to learn how to use your mobile phone? If no, then try to learn English