Please help a newbie. I thought I had plotting done

You can’t farm plots that aren’t on our pool nft with FlexFarmer.

Given that there are compressed plots now though, you may be better off just replotting for them.

If you use this guide Gigahorse Ubuntu Simple Plotting Guide you can plot and farm (using FlexFarmer) without ever syncing the node then run the client in light wallet mode. However, those plots will be locked to Flexpool.