accommodation and visa requirement to botswana

Hi, am a tennis coach and am taking my team to Gaborone in Botswana for a junior tennis programme, can anyone pls tell me how to get the visa as Botswana doesnt have embassy in Nigeria.

Also, i need to book for hostel or hotel for my team, how will i get a cheap or average hotel fee. For the hostel/hotel, i wil be needing three rooms. It must be closer to the championship centre.

The site of the championship is - National Tennis Centre Gaborone Botswana 15479 Segoditshane Way (Notwane Courts)