Role/Grammar of 找 and 跟 in "他找白如玉跟他在師大附近走走"?
他找白如玉跟他在師大附近走走, 試試地圖好用不好用。


让她(ask her) is implied in this sentence. So, it can be reworded: 


  他找白如玉让她跟他在師大附近走走, 試試地圖好用不好用。


他找白如玉: he looks for 白如玉; 跟他: with him; 在師大附近: near/around shida; 走走: have a walk; 

Put all pieces together: 


  he looks for 白如玉 to/and ask her to have a walk with him around Shida. 


You should be aware that sentence order between English and Chinese is quite different sometimes. 

Hope this could help you out.