Can someone explain the land purchasing process as it relates to homesteading in Montana circa 1915?

I am researching an ancestor who purchased land (most likely through the Homestead Act) in Fergus County, MT in about 1915-1916.  I have located Records of Patent (dated 13 Oct 1915) for land purchased under the Bureau of Land Management website. I have copies of public newspaper notices for "Public Land Sales" published in May & June 1915.  I have researched how the Homestead Act worked.  I would also like to know if there are records available for when a land parcel is relinquished (i.e. not meeting the Homestead qualifications).  What I need is someone to explain the "legalese" of the Records of Patent and the public notice.  

Can you point me to a website or resource who can help me?

Thank you,

Ramona Nahorny