@Howard ********
When you purchased the condo it should have been registered at the Land Office and you should have received a blue house registration book (tabian bahn in Thai). That book will contain all the information you need to register yourself using the online TM-30 app from Thai Immigration. Even without the blue book you *may* be able to register yourself using the app. However, there will come a time during the registration at which they need you to upload a copy of the blue book (first page) and a copy of your passport ID (photo Id page). They have recently migrated from the old TM-30 app to the new one and it seems that they may not be currently rigorously checking for supporting documentation so you may be able to proceed without your blue book.
First thing, go to the official TM-30 website and register for a TM-30 account (click the blue Register link):
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You should receive notice by email when your account is approved (may take a day or two). Log into your account. Note you only have to create the account once, but you must retain your login information (email address and password).
Enter the information for your property, including information about yourself as owner. Note that this is done through the Profile menu (not exactly an obvious place). Then you should be able to report that you are staying at your property by clicking Add on the main page.
Then (within seven days) you need to search the system for your report. Enter only the from and to dates as the search criteria. Note that you can only search for the last seven days. When you see your report, see that it says its status is informed, then click on the download pdf of your report details and print that out and staple into the back pages of your passport. That is your TM-30 receipt. It remains good as long as you live at your address.