There are two "Islams". The first is the religion which spread primarily through peaceful interaction or the benefits it provided under the stewardship of an Islamic State. The second Islam was an actual Empire or Islamic State which expanded through warfare and conquest. It is necessary to understand that while the Islamic Empire grew through warfare, most conversions to Islam were not compelled.
by. Sending messengers around to different places with letters explaining what Islam is to the rulers of the different places and inviting them towards Islam
It spread to places in Saudi Arabia and Syria
India, Africa and Southeast asia
Indonesia, West Africa, China and the Philippines
Islam first started in Makkah (Saudi Arabia), and then spread to Madina. After that, Muslims would travel around the world (the entire world), and teach people about Islam, and what it's all about.
Islam spread to libya by other countries
Islam first spread along TRADE ROUTES since merchants could often bring the religion to places too far away to effectively conquer.
A struggle or conflict to spread Islam is a Jihad
Islam never spread by war. Refer to question below.
Islam spread north at first and then spread east and west.
All over the world although with different percentages to total poulation in different countries
It was spread in Arabic.