diff --git a/README.md b/README.md
index cd51531d0fb070d8d26d5f704837b9ecc7837def..59d0333401533f9d40bea278ddecaa40b51b0b7f 100644
--- a/README.md
+++ b/README.md
@@ -56,6 +56,31 @@ The `csst_proto` uses an awesome algorithm based on `numpy.ndarray` indices to f
---
+## `git`: connecting collaborators
+
+A very brief example of using `git`:
+
+```bash
+# global setting for git (name and email address)
+git config --global user.name "BO ZHANG"
+git config --global user.email "bozhang@nao.cas.cn"
+
+# initialize a repository with main branch
+git init --initial-branch=main
+# clone a remote repository
+git clone https://csst-tb.bao.ac.cn/code/csst-l1/csst_proto.git
+# add some_module.py to version control system
+git add ./some_module.py
+# commit the changes
+git commit -m "added some_module"
+# add remote repository link
+git remote add origin https://csst-tb.bao.ac.cn/code/csst-l1/csst_proto.git
+# push changes to remote repository
+git push origin main
+# pull remote updates
+git pull origin main
+```
+
## timeline
| file / directory | description | urgent | C6 | C7 |
@@ -92,24 +117,29 @@ The `csst_proto` uses an awesome algorithm based on `numpy.ndarray` indices to f
- gitlab CI/CD pipeline available
- auto unit tests passed with `.gitlab-ci.yml`
- stage 6:
- - *sphinx-based documentation available
+ - sphinx-based documentation available
- `doc/`
- `readthedocs.yml`
## progress
-| module name | stage 1
(source code) | stage 2
(installation) | stage 3
(instruction) | stage 4
(unit tests) | stage 5
(gitlab pipeline) | stage 6
(sphinx doc) |
-|--------------------------|--------------------------|---------------------------|--------------------------|-------------------------|------------------------------|-------------------------|
-| `csst_proto` | √ | √ | √ | √ | √ | √ |
-| `csst_ms_mbi_instrument` | | | | | | |
-| `csst_ms_mbi_distortion` | √ | √ | √ | | | |
-| `csst_ms_mbi_position` | | | | | | |
-| `csst_ms_mbi_flux` | | | | | | |
-| `csst_ms_mbi_photometry` | | | | | | |
-| `` | | | | | | |
-| `` | | | | | | |
-| `` | | | | | | |
-
+| module name | stage 1
(source code) | stage 2
(packaging) | stage 3
(instruction) | stage 4
(unit tests) | stage 5
(gitlab pipeline) | stage 6
(sphinx doc) |
+|---------------------------|--------------------------|------------------------|--------------------------|-------------------------|------------------------------|-------------------------|
+| `csst_proto` | √ | √ | √ | √ | √ | √ |
+| `csst_ms_mbi_instrument` | | | | | | |
+| `csst_ms_mbi_distortion` | √ | √ | √ | | | |
+| `csst_ms_mbi_position` | | | | | | |
+| `csst_ms_mbi_flux` | | | | | | |
+| `csst_ms_mbi_photometry` | | | | | | |
+| `csst_ms_sls_instrument` | | | | | | |
+| `csst_ms_sls_mosaic` | | | | | | |
+| `csst_ms_sls_position` | | | | | | |
+| `csst_ms_sls_distortion` | | | | | | |
+| `csst_ms_sls_directimage` | | | | | | |
+| `csst_ms_sls_sky` | | | | | | |
+| `csst_ms_sls_axe` | | | | | | |
+| `csst_ms_sls_cde` | | | | | | |
+| `` | | | | | | |
## useful links