Once you login you will go to your Portfolio page. There you can just enter the symbol and a list will appear as you type in to select your symbol from. Once selected, click on Add Symbol.
If you have multiple symbols to upload, just click on the Setup tab on your Portfolio page. Then click on the Import Stocks (and ETFs) to your Portfolio link. There you can quickly type in your symbols, separated by a space and comma. See screenshot below.
And if you have so many symbols that you want SmartStops to bring the list in, please just Contact Us and we can help.