If you entered the given address you saw a form where you can enter a file name and the content for the file.
But this form wasnt really important for this challenge. When you upload a file you get redirected to
```
http://host/myfirstweb/index.php?op=view&file=filename
```

The first thing i tried was to test if we can open the 'flag.txt' file directry with
```
http://host/myfirstweb/index.php?op=view&file=./flag.txt
```
But the site refuses with "Found flag format in content, no flag for you!"

I tried to enter the flag file directly with
http://host/flag.txt

and here we go

`Flag: BAMBOOFOX{0hhh_n0_s7up1d_li77l3_8ug}`