To add an asset to your account, you first click on the add asset button on the home page. Then enter the add asset page.
Here, there are two tabs.
In this section, there is a list of famous assets that you can find by searching a few characters of your desired asset. By selecting it and clicking on Add Button, add that asset to your account.
In this section, enter the information of the asset you want to add, such as asset code, asset issuer, limit, and then click on the add button to add that asset to your account.
When you add an asset to your account, you are originally creating a trust line between the account and that asset. For more information about the trust line, see the Stellar document.