You can use either online version of the client, or standalone version for Mac, PC or Linux. All versions support automatic update. Also downloads are available from the official site - https://wavesplatform.com/product
Choose and open up your Waves wallet.
Click on Restore account on the main page.
You will be forwarded to the following page. Copy and paste or type your SEED into the blank text field. The Waves wallet will automatically generate the corresponding address right below the text field.
If you entered the correct SEED, it will display your Waves address. Choose account name and wallet password then repeat the password.
To finish the process, click on Sign in
At the final stage, read carefully the conditions and if you are agree put the checkboxes. Click on Confirm and Begin.
If you have done all of the above, you are forwarded to the user interface