Teaching the use of GIS software is beyond the scope of this website. Links will be provided in the "Using Data" section to training material available on the internet for using QGIS the open source software that that is referenced in the website. There is more information in the section "Open Source" on downloading the software.
QGIS can load data in a number of formats but the most common are probably "shapefiles" and spreadsheet tables. The shapefiles are loaded directly while spreadsheet tables and other formats often require some kind of formatting. Data for use in GIS analysis will be listed under the various headings along with national and subnational data. Data which does not fit into the designated categories includes the basic global national and subnational outline files, for which sources will be given below. Also given below are links to two sites which provide shapefiles containing detailed current data from OpenStreetMaps (OSM). The OSM mapping is done by volunteers and completeness of areas mapped varies from country to country--much progress has been made recently in the mapping of developing countries.The sites selected for the various sectors provide global country-level data or at least data for a number of countries.
Outline Maps--There are many sources of "shapefiles" which provide global, regional, national and sub-national outline maps onto which other data can be superimposed. A short selection of sources of this type of data are listed below.
WORLD BANK--The World Bank provides a range of country profile shapefile maps at World Bank Boundary Files click on the "Data and Resources" tab.
GADM--GADM provides access to country map outlines with several layers of administrative sub-divisions. Data can be downloaded country by country or the whole database can be downloaded https://gadm.org/index.html .
Statsilk--This site provides links to country and sub-national outline shapefiles as well as outlines for individual countries, and links to other GIS resources. Click http://www.statsilk.com/maps/download-free-shapefile-maps.
HDX-- This United Nations data set provides shapefiles, including boundary areas and sub-administrative areas at https://data.humdata.org/dataset. There is a box for entering country names and other search data in the top left corner of the page.
Natural Earth-- Provides a range of global map outlines. Click http://www.naturalearthdata.com/downloads/.One note of caution, if you are linking data to the outline map from a spreadsheet for example, and linking on the three character ISO code, Natural Earth uses the code SDS while most spreadsheets will use the ISO code SSD. It is usually easier to change the code in the spreadsheet.
South Sudan-- Many map collections do not include South Sudan
(SSD) -- mapping for South Sudan is available at https://data.humdata.org/dataset/south-sudan-administrative-boundaries
(The file name is ssd_admbnda_imwg_nbs_SHP.zip.)
DIVA-GIS--Provides country level and world level shapefile outlines at https://www.diva-gis.org/gdata. Unfortunately the data is somewhat out of date and neither the global or country maps include South Sudan.
Mapcruzin--Contains links to a large number of shapefiles at https://mapcruzin.com/download-free-arcgis-shapefiles.htm. The African maps do not seem to include South Sudan. Data updates appear to have ended by 2019.
Finding Shapefiles-- There are far too many sources to list. Many countries supply specialized outline shapefile maps--Canada for example provides shapefiles for census areas and outlines of treaty boundaries for indigenous "First Nations". A search for "Zimbabwe roads shapefile" brought up 10 links.