Sorry ... I'm not that connected
As your computer is booting, watch the screen carefully for a keystroke command which will take you to the BIOS.
In most cases,
simply pressing the delete key several times as the computer is booting will take you to the BIOS,
but some systems may require the *F3* key or something similar. This information will appear on your computer screen --- you may have to re-boot several times - it pops up quite fast.
Once you have entered the BIOS look for a menu called *Boot* or *Boot Sequence* -- verify that your boot sequence is correct with the HDD with your OS first in line.
You may use your 'arrow keys' or possibly the '+/- keys' to move around the menus and options in the BIOS. There will be instructions explaining this to you.
Once you have properly set the boot sequence, press the *F10 key* to save your revisions and exit the BIOS.