First, look in the upper right corner of your Firefox window, and find the button icon that looks like three horizontal lines. Click on the three horizontal lines, and from the menu that drops down, click the Options icon.
Once in Firefox Options, click on the "General" tab and locate the area where MySearch.com is entered as the Home Page. Using your mouse, select the MySearch.com page address, delete it, and type the address of whatever page you'd like to be your default, as shown below (for example, if you'd like Facebook to be your homepage, type in www.facebook.com).
That's it for your default homepage settings! After making the change to your default homepage, you'll need to open a new Firefox window to see the change. Changing your homepage setting doesn't retroactively affect pages you already had open prior to making the change.
If you want to remove the MySearch New Tab page, please follow these instructions on how to remove the add-on from Firefox.
Next, if you want to change the default search engine for Firefox, you can access the option by clicking on the magnifying glass icon, found in the search box on the top-right corner of the browser. When you hover the cursor on top of the icon, you will see a triangle icon appear. Click on it to see the list of available search engines, which can be used for your next search. If you want to make a specific search engine the default, click on the last item: “Change Search Settings." This will open Firefox Options to the appropriate section. Under “Default Search Engine," pick the search engine of your choice from the drop-down menu. Then close all Firefox windows and reopen Firefox to see the changes in effect.