"How can we spread Esperanto?"
Translation:Kiel ni povas disvastigi Esperanton?
First note that there are not strict rules in Esperanto, when to use capital letters.
There are three kind of language names in Esperanto.
• with a capital letter and no article: only Esperanto itself
• other names ending in -o (latino, sanskrito, hebreo etc.) Many nowdays write these without a capital letter and article. However one of the most important grammar books PMEG prefer either with a capital or with an article.
• all other language names end in -a (la angla, la araba, la hinda etc.) and these are written with the article and are considered abbreviations of la angla lingvo, la araba lingvo, la hinda lingvo etc. Once again PMEG for some reason capitalizes these.
I prefer the simplest writing, i.e. only Esperanto with a capital and those with o-ending without the article. IIUC Duolingo uses this.