You can edit the content on your page by clicking on Edit located at the top of your site on the Admin Bar. Once the editing interface comes up you can click in any of the editable areas.
There are two different ways of adding content to your site. The first way is dealing with Text content and the second is called Blocks. To add text to your page. Click on the Edit button on the Admin Bar at the top of your site. Once the editing interface comes up click inside of the of an editable region, marked by the blue border, and start typing. Once you do that publish your page and you are done.Now when you want to add an image to your page you create a block for that image.
To create a link on your page select the text that you want to link. A small black box will pop up above the selected text. To link it click the chain link icon and type in what you want to link to.