Looks like Tom to the rescue with a tutorial below.

The following can help: https://themeisle.com/blog/change-wordpress-profile-picture/ How To Change A Wordpress Gravatar Step 1? Your WordPress credentials can be found going to:
https://my.wealthyaffiliate.com/websites
Tom

you would have setup a wordpress account when you created your gravatar, so worth checking your emails for your login detais
it should be your email address for the site.
i would start to write down login details in a n offline book just in case your computer crashes .
don't forget to take a note of your site login details.
good luck
phil

In your WordPress Admin page,

scroll down to "Users" on the left.
Click "your profile"
Scroll down to your picture
There's a link under your picture saying you can change your Gravatar there is.

Does this help?

Helen got you covered below. Good luck.

Hi Cath, there are two places you can go to change your theme. You can go to your dashboard and under appearances there is a tab for theme, you can do it there or you can go to customise and change your theme from the customise screen.

You can use any of the free themes but if you decide to buy one, you will need to import it as a zip file and upload it and you can then do the same with it as you do with any of the free themes.

Hope that helps. Message me if you get stuck !