Click Indicators in the top bar, or press /. The library is one searchable list, with official OpenMarket indicators and community scripts side by side. Search understands abbreviations such as "rsi" or "vrvp", and the round buttons above the list narrow it to favorites, official, community or your own scripts.
Click Add on a row and the indicator draws at once; hold Shift while you click to add it to every chart in your layout. Its legend row then appears at the top left of the chart: the gear opens its settings, the eye hides it and the cross removes it.
Saw an indicator on someone's chart and do not know its name? Browse the categories (Trending, Volume Footprints, Technical and the rest) in the indicator library guide.