To add a Work Record to a site through the data grid, you must first select a site via the checkmarks at the left side of each record.
Then after the site is selected, click the Add Work button in the panel to the left of the data grid.
If you want to add the work record to multiple sites simply checkmark multiple sites on the data grid and the Add Work button will allow you to add a work record to all those sites at the same time.
From here, you will be brought to the work record page where you can either fill out the information manually, or if you need to use a previous work record that you have viewed, you can use the Load Last Work Record button at the top of the window to load the information from the last work record you viewed.