Hi, you want to go to your clan page and find the "edit" button on the first post of your clan. Then when you're editing your post make sure you have the link and find the icon that looks like this
it's right by the
B I U icons. After you click the insert link icon paste your link into the box that shows up for your respective browser. After you insert the link it will highlight the link you pasted, you will be able to rename the highlighted part to anything you want.