Here a two other references that might be of interest when starting with MaxEnt:

Merow, C., Smith, M. J., & Silander, J. A. (2013). A practical guide to MaxEnt for modeling species’ distributions: what it does, and why inputs and settings matter. Ecography, 36(10), 1058-1069.

Elith, J., Phillips, S. J., Hastie, T., Dudík, M., Chee, Y. E., & Yates, C. J. (2011). A statistical explanation of MaxEnt for ecologists. Diversity and Distributions, 17(1), 43-57.

We have applied MaxEnt for modelling fish distributions/habitat quality based on occurence records only in a small German river network:

Radinger, J., & Wolter, C. (2015). Disentangling the effects of habitat suitability, dispersal and fragmentation on the distribution of river fishes. Ecological Applications.

http://onlinelibrary.wiley.com/store/10.1111/j.1600-0587.2013.07872.x/asset/j.1600-0587.2013.07872.x.pdf;jsessionid=047B622EE98E10AE33E4F5D6770295D3.f01t04?v=1&t=ijv3m07x&s=70ae4c26ba0442e8c2c6284b786e9a1048c84554

http://onlinelibrary.wiley.com/doi/10.1111/j.1472-4642.2010.00725.x/abstract

Dear Martina,

Please find the MaxEnt tutorial in the attachment, it may solve your problem.

Best Wishes,

P