Can someone please help a very stupid idiot with their Vanguard Roth IRA? I just opened it and have no idea how to put 100% of my money into their boring VOO.

EDIT - Solved. Yes, you do indeed have to click 'Trade ETFs & Stocks' and on that web form you can choose to buy in 'shares' or 'dollars' and you're able to buy fractional shares using the 'dollars' option. Thank you to everyone for their responses. \--- I just opened a Roth IRA with Vanguard on 1/12/2026 with $500 and that's all I've done so far. Before plowing another $7000 to max it out, I'd like to make sure I have everything set up right first. When I log into their website now on a desktop PC, I see that yep, there's $500 sitting there. Ok, now what? How do I put 100% of that $500 and all future contributions into a boring, no-touch index fund? Do I have to click the 'Transact' button near that account and click...'Trade ETFs & Stocks?' I tried going through those motions, but I don't think it'll let me because 1 'share' of VOO is apparently $636 and I only have $500 dollars in the account. That's probably not the right thing anyways. If you maxed $7500 already and wanted to 'buy shares,' you could only buy 11 shares and have leftover money that's not invested in anything. I don't want to 'buy shares' of anything. I just want to put 100% of my money into VOO, and as I continue to make contributions, have THAT money ALSO automatically be invested in the VOO as well, so I'm confused. Do I want to put my money in a 'holding' or something? I just want the most simple, boring, lowest-fee thing where I set it up so that the current money and all future contributions stay in their VOO and I never have to touch any buttons ever again other than when making contributions every year. Any help would be appreciated, thank you.