Hello, i recently followed a tutorial online teaching me how to softmod my Wii and i did exactly as he said. I installed the homebrew channel and BootMii through this program called letterbomb. After that i got my usb and i created a folder called wbfs and in the folder i dragged a 300 mb game into it. I then put my usb in the second usb slot and i went to the homebrew channel and i clicked WiiFlow. I then saw my game, so i connected to wifi and i installed the cover art for it. So i click the game then i click play but as soon as i clicked play it just brought me right back to the game menu were you have to option to either click play or some other option. I honestly don't know what to do. Oh and i forgot to mention i also did this iso365 patcher or something similar to that.
My wii version is 4.3U
You likely followed some obsolete and/or incomplete guide. There are many steps missing from what you stated you did.
Installing HBC isn't "modding your system". It's using an exploit to install one piece of software.
What happens after you install HBC is the "modding" process, which sounds like was missed and you attempted to go right into wiiflow.
Check the softmod any wii guide for how to properly mod your system. Then check the FAT32 guide for recommendations on how to format and install content to a hard drive.
Both guides are linked in my signature.