Theme Horse

Hi Samuel,
first of all download the zip theme(interface-pro) and then first unzip the file and rename it(interface-pro-v-1.0.1) rename it. After renaming it zip the file
Then go to dashboard-> appearance-> themes-> add new
and upload that zip theme. The same two theme will be shown there and preview the theme. You can find the new one with its latest version after clicking on Theme details.(You can identify it from the latest version)
Then active the latest version.
Delete the old version of the theme.

The next way is from ftp
go to ftp of your site
inside wp-content->themes
upload the new version of the theme and before doing that first rename the older version of theme.

After completion upload of the new version theme you may delete the old version of theme.
Thank you