Once installed, you can give the plugin access to your 88 Miles account, by clicking options.
Click the Authorize button and you will be asked to approve access to your account. Enter your login and password, and click Authorize App
Now, you can navigate to your Basecamp, click on a project and you'll see a new Time Tracking section. You will need to tell Basecamp which 88 Miles project to use — select it from the dropdown and click Link.
If you want to start work on a to do list item, just click the clock next to it.
If you just want to punch in to this project, you can click Start next to the Time tracking header.