Get the latest version of SKSE compatible with Skyrim 1.1.47 from the official SKSE website or a reputable modding site.
But remember: the “top” of yesterday is not the peak of today. For anyone but the most dedicated retro-modder, updating to Skyrim 1.9.32 (or better yet, Special Edition) will give you access to a larger, more stable, and more vibrant modding community. skse for skyrim 1147 top
For (often referred to as the latest "Anniversary Edition" or "AE" build on Steam/GOG), you need the corresponding version of the Skyrim Script Extender (SKSE) to enable advanced modding features. Core Installation Guide for SKSE (v1.6.1170) Get the latest version of SKSE compatible with Skyrim 1