Where is transmission oil input plug or location
I’m presuming this car has an automatic transmission. If so, that info should be in your owner’s manual, or possibly on a sticker on the under-side of the hood. Note that on some car designs, the transmission fill isn’t easily accessible, thinking is that only a shop with shop equipment would do it.
If you don’t have the owner’s manual, you can probably download a pdf electronic version from the Kia website.
A lot of them now are underneath by the axle and the car may need to be level and the fluid at a certain temp. A lot of them don’t have dip sticks so I don’t fool with them anymore and just take it in. But yeah see what the manual says and don’t listen to Manuel. 
Tester