Thanks for the info.  Yes, the 390 has Secure Boot.  As for TPM, it might be 1.2.  I'm pretty sure it's not 2.0.  I Googled away at it and couldn't find anything concrete.  It's found in Security in BIOS if it has it. TPM did not come up in the spec sheet, Tech Guide, and Owner's Manual. Are you looking to install Win11?  If you are, you can likely Google the instructions and/or videos.
yes, I'm new to this place I once had an HP laptop before I got this dell optiplex for my birthday. so I got a question does the dell optiplex support TPM and secure boot? 
Hey guys im kinda new to this place.