Here are the steps for adding a button
1) Download Ribbon Work Bench solution from the following linkDownload Ribbon WorkBench
2) Import the solution to CRM.
3) Create a solution with the entities and web resources where you wanted to add a button. In my case, its on Opportunity.
4) Go to CRM-> Settings->Solutions.
5) You will see a link with name “RIBBON WORKBENCH” as shown in the below screen shot.
6) click on link and it will open a pop-up to select the solution to open.
7) The workbench all the information related to the entities from the solution.
8) Click on Ribbon tab button as shown in the figure.
9) You will see a dropdown on the top right side window for selection place to show the ribbon button. In my case, I would like add a button on the Opportunity Form.
10) Drag the button from left and release it in the place where you wanted to create a button.
11) Select the button and give the details like label, description, Image etc..
12) Select Commands and click on Add New
13) It will create a command for you. Expand Command and right click on the command. It will display you to select Display Rules, Actions and Enable Rules.
14) Select Actions and it will open a pop-up.
17) Expand Buttons and select the button which was created.
18) Click on Command dropdown as shown in the screen shot. You will see the command which you have created, select that and click on Publish button on the top.
19) Click on Publish button.
Here is the output.
Hope this helps.