dont feel bad i too was once clueless when i got my first yorkie
if for any reaso your not able to get the nutri cal you can even use maple syrup try to not let her get too overworked because shes so young play for shorter periods of time and try to free feed this is leaving food out all day for her at this age her appitite may be very picky later on you can put her on more of a schedule. p.s dont ever feel silly to post a concern or question im sure everyone here including myself are more than willing to help you with your new furr baby