Help with Old School Essentials character sheet

So me and some friends are new to the Basic D&D style games, we got the OSE book, and saw there was an OSE character sheet already made for roll20, nice!    I just had a question or two about what to fill in where.  I'm not sure I understand the attack matrix on the sheet and what goes where, as I haven't filled in an attack matrix before on the sheet.     Is there a spot on the sheet for THAC0?  What do you put in the "Exploration" entries,  the chance-out-of-6?  so, if it was 1-in-6 would you put 1?  Is HD basically like.. if you have d6 for your hit die, you'd put a 6?  Thanks for any help understanding these extra entries. 

Hi John, I'm not really familiar with the sheet(but I'm older gamer...), I'm guessing you enter a THAC0 value next to the "0" column and the rest of the attack matrix will auto adjust. I believe you put the upper threshold on your checks. Ranging from 1=you aren't too good thru 6=your great. I think your correct on Hit Dice, just enter the die size. Cheers

Vince said: Hi John, I'm not really familiar with the sheet(but I'm older gamer...), I'm guessing you enter a THAC0 value next to the "0" column and the rest of the attack matrix will auto adjust. I believe you put the upper threshold on your checks. Ranging from 1=you aren't too good thru 6=your great. I think your correct on Hit Dice, just enter the die size. Cheers Okay, yes I think I understand now, thanks for pointing it out!  I put my THAC0 in the place where the zero AC was on the matrix and the handy thing filled out the rest for me, very nice.