Windows 11 Secure Boot

[globeq]

So, I've recently started to look at windows 11 more and more and realised I don't have my secure boot enabled (I've enabled TPM 2.0 module if someone's interested) What I'm trying to ask is How do I turn it on, I have a:
Gigabyte Z370 HD3 motheboard
F5 version of BIOS 
The problem is I can't find any tutorial on this, It shows I have a legacy BIOS in system information and I have no idea where do I turn on the EUFI one, or I just simply can't. Please help, thank you for your replies.

 

Also, I've tried one thing, turning on the secure boot thourgh BIOS, but it said I couldn't do it so I turned off my PC and turned on again, after that BIOS instantly showed on my SECOND monitor and I still couldn't turn it on, the situation repeated after I didn't turn off the secure boot in BIOS, I don't know what's the problem... Please help me again.

My specs:
MSI GTX 1050 TI Gaming X
Intel i5-8400

Gigabyte Z370 HD3 Motherboard

[LogicalDrm]

-> Moved to Windows

***

 

Your board doesn't have it integrated, but you can install it like any additional hardware. Buy the chip, plug it in and it should be activated automatically.

[globeq]

What chip, what do you mean, to my knowledge you can buy a TPM chip but I already have it integrated