Consider posting some excerpts you are having problems with. Most of the Holmes stories can be found online at no cost at Project Gutenberg, http://www.gutenberg.org
so you can copy-and-paste passages.
The Sherlock Holmes stories are NOT written in easy English. Moreover, they reference many details of Victorian life that are not necessarily familiar to native English speakers. NOBODY knows what a "tantalus" or a "gasogene" is unless they look it up.
I actually own a big three-volume set, "The New Annotated Sherlock Holmes," edited by Leslie S. Klinger. I love the stories, but I do find the notes helpful. If you are ENJOYING the stories you may want to see if your library owns a copy. In addition to background on the times and the culture, he also points out numerous logical problems and flaws and holes and inconsistencies in the plot!
Unfortunately, Klinger is one of those "Holmesians" who enjoys keeping up a pretense that Holmes was a real person...