About this 7/11 ad?

I'm new here in Japan and still learning. And one of the things that really excites me of being here is being in the land of pure anime goodness and more! To add to that, I got the chance to be here when my favorite manga,Rurouni Kenshin was released on big screen! Now every RK ad I see haunts me!xD

Can anyone please help me give some info as how to enter this contest? I can only understand some bits but I really want to know the details..please?

https://cam.sej.co.jp/cp/CAPC080.do

Yoroshiku onegaiitashimasu m(_ _)m

Just an overview:

Per every 350 yen purchase of rice products (rice balls, "bento" lunch boxes, sushi packs, etc. - frozen rice products are excluded) at Seven-Eleven, on your receipt you get a serial number, which you can sign up on this website and accumulate (on your account created here on the web). Once you've accumulated enough points to enter the sweepstakes for the prizes listed, you can spend the points and enter the sweepstakes (lottery).

Purchases made during the period of Aug. 25 to Sept. 14 will be eligible (be careful which products are eligible), and you can enter until Sept. 16.

Thanks so much for that AK! I think that's why I didn't get that serial number on my receipt since I bought onigiri and some frozen goods even if it was over 350yen :(
I'll just have to do with onigiri and bento just to be safe,lol!

By the way, what's that red/white card with circles on it? I thought everything's going to be done online?

The card at the bottom with the small circles on it? That's the sticker (of course the circles in reality will be the product name and the price) on products that are eligible for this campaign.

P. S., I read it again and what they mean is:
THe products eligible are:
- Rice balls, bento boxes, sushi packs, etc.
AND
- Other (non-food) items that come with that sticker, indicating that they are "affiliated" products.

I thought it was like a stamp card :)
I'll just have to make sure which items have that sticker then, aside from the bento and onigiris I've already set my eyes on xD
thanks again AK! I'll let you know if I'll be lucky on this lottery,lol!